Multiplex Bolting Tool

ABSTRACT

A torque wrench for multiple bolts or nuts comprises multiple drive spindles that are arranged annularly around a center and are equipped or able to be equipped at the end with respective torque-applying tools, and a ratchet drive, associated with each drive spindle and driven by means of a hydraulic piston drive, for driving the drive spindles. The torque wrench for multiple bolts or nuts also comprises an actuator unit for inducing a rotary movement in the drive spindles, having an actuating wheel mounted rotatably about the axis of the center of the annular arrangement of the drive spindles as drive wheel, which drives respective output wheels fitted on the drive spindles, wherein the driving movement of the actuating wheel is transmitted to the drive spindle via respective torque limiters.

BACKGROUND

The present disclosure relates to a multiplex bolting tool, also calleda torque wrench for multiple bolts or nuts with multiple drive spindlesthat are arranged around a center and are equipped or able to beequipped at the end with respective torque-applying tools, and a ratchetdrive, associated with each drive spindle and driven by means of ahydraulic piston drive, for driving the drive spindles.

Torque wrenches for multiple bolts or nuts serve the purpose of applyingtorque to a plurality of screw connections in a single screwing processand thus, for example, tightening or loosening bolts, which are arrangedin a ring arrangement. Simultaneously applying torque to a plurality ofscrew connections shortens the time otherwise required for applyingtorque to several screw connections. Furthermore, when applying torqueto individual screw connections, which are arranged annularly around acenter, care must be taken to ensure that the components to be boltedtogether do not tilt relative to each other, which is why the screwconnections must be tightened according to a predefined screwingpattern. If this is not adhered to, there is a risk that a jointconsisting of several bolted connections will not be fastened properly.

Torque wrenches for multiple bolts or nuts are used for connectingrisers in oil or water wells, for example. At their ends, these pipeshave connecting flanges protruding outward in the radial direction. Toconnect two such pipes, the adjacent connecting flanges are boltedtogether with several screw connections. A torque wrench for multiplebolts or nuts suitable for this purpose is known from EP 2 288 476 B1.With this previously known torque wrench for multiple bolts or nuts, anumber of torque-applying devices corresponding to the number of screwsto be tightened or loosened is provided, for example six torquestations. The torque stations are arranged around a center. Thispreviously known torque-applying device is designed in an annular shapeand leaves a central opening through which the pipes with their flangescan be pulled. Each torque station is displaceable in the radialdirection, such that it can be adjusted from a non-operating position,in which a riser with its flange can be passed through a central openingof the torque wrench for multiple bolts or nuts, into an operatingposition for applying torque to the screw bolts. In order to applytorque to the screw connections of two adjacent connecting flanges ofsecond risers, the torque stations are displaced in the radial directionto their operating position. Each torque station has a drive spindle,which drives a socket as a torque-applying tool. The socket has an innercontour, which is complementary to the outer contour of the head of ascrew bolt that is meant to be tightened or loosened by means of thetorque station.

Each drive spindle is driven by its own hydraulically operated ratchetdrive. For this purpose, the piston rod of a hydraulically actuatedpiston is connected to the ratchet lever of the ratchet drive. Theratchet lever has a pawl, which drives a drive spindle that is rotatablysupported in the ratchet lever. The drive spindle has a square opening,into which the square drive, which has a complementary geometry to oneend of a socket as a torque-applying tool, can be inserted. The pawl isunder spring preload and interacts with the outer splines of the drivespindle under the spring preload. With a forward stroke of the pistonrod, the drive spindle is advanced by at least one tooth, proportionalto the executed stroke, relative to the pawl. With the return stroke,the ratchet lever is returned to its initial position, while the boltdoes not turn back. This alternation between the forward and returnstroke is carried out until the bolt is tightened with the intendedtorque.

In such torque wrenches for multiple bolts or nuts, it is sometimesdifficult for the torque-applying tools located on the torque wrench formultiple bolts or nuts to mate their inner contour to the outer contourof the parts of a screw connection to be driven, for example the head ofa screw bolt. In such a torque wrench for multiple bolts or nuts, thetorque-applying tools are typically pre-positioned with respect to theirrotational position and with respect to their contour to match the partsof the screw connections to be driven. In addition, the individual screwconnections of such a joint with multiple bolts should be tightened withthe same torque. In the case of screw connections, which are to betightened with a high torque, e.g., 200 Nm or more, this cannot berealized with simple, reasonable means via torque-limiting slipcouplings installed in the individual ratchet drives, especially sincesuch a ratchet drive would be prone to wear.

SUMMARY

Proceeding from this background, an aspect of the present disclosure isto further develop a torque wrench for multiple bolts or nuts in such away that it is possible, in a simple manner and before tightening orloosening the bolt, to mate the complementary contours between torquetool and the part of the screw connection to be driven, and also totighten the screw connection, even with high torques, without installingtorque limiters in each individual ratchet drive.

According to the present disclosure, this aspect is provided by ageneric torque wrench for multiple bolts or nuts of the type mentionedat the onset, in which the torque wrench for multiple bolts or nutscomprises an actuator unit for inducing a rotary movement in the drivespindles, having an actuating wheel mounted rotatably about the axis ofthe center of the annular arrangement of the drive spindles as drivewheel, which drives respective output wheels fitted on the drivespindles, wherein the driving movement of the actuating wheel istransmitted to the drive spindle via respective torque limiters.

This torque wrench for multiple bolts or nuts has an actuator unit,which is actuated before the actual tightening or loosening processbegins. The drive spindles can be moved with this actuator unit. Forthis purpose, the actuator unit has an actuating wheel, which is mountedrotatably about the axis of the center of the annular drive spindles.This actuating wheel is a drive wheel and drives respective outputwheels that are seated on the drive spindles. In this manner, a drivingmovement of the actuating wheel can be transferred to the drivespindles. A particular property of the actuator unit is that thetransfer of the driving movement of the actuator wheel to the drivespindles is performed by means of respective torque limiters. Thepurpose of these is to ensure that the screw connections to be tightenedcan be tightened with equal torque by means of the actuator unit on afirst pass. The actuating wheel can be operated manually, for examplewith a ratchet as a drive tool or with an electric screw tool. Ofcourse, it can also be operated hydraulically or pneumatically. Thetorque introduced into the actuating wheel is limited. Due to therotational movement of the actuator wheel and the resulting rotationalmovement of the drive spindles at the torque transmitted via the slipcouplings, the torque-applying tools seated on the drive ends of thedrive spindles are rotated. The torque-applying tools are typicallyspring-loaded torque-applying tools, which can be adjusted in thelongitudinal axial direction by a certain amount against the force of areturn spring on the drive spindle. If, when actuating the actuatordevice, the torque-applying tool for multiple bolts and nuts is heldagainst the fastening elements, for example, the bolts, thetorque-applying tools executed in this embodiment as sockets snap ontothe bolt heads when their respective, complementary contours are alignedwith each other. Thus, by operating the actuator unit with a low, inparticular manually transferred, torque, the torque-applying tools caneasily mate to the respective complementary contours of a fasteningelement and thus engage with them.

The torque limitation in the transfer of torque from the actuating wheelto the drive spindles serves the purpose that the fastening elements—forexample, the bolts—driven by the drive spindles via theirtorque-applying tools, are tightened until the slip coupling engages anda transfer of further torque to a drive spindle is no longer performed.The torque limiters of the individual drive spindles, which are designedas a slip coupling, are set up in such a way that the torque limitationapplies to each drive spindle at the same torque. In this manner,differently tightened fastening elements can be put into a preloadposition, in which they are all tightened with the same preload. Thesubsequent operation of the multi-tool for tightening the screwconnections by means of the ratchet drives thus starts out from the samepreload with regards to all screw connections to be tightened. Thispreload does not need to be particularly high. It merely serves thepurpose of ensuring that the screwing process begins from the samestarting point for all screw connections with respect to the preloadapplied. It is then possible to drive the drive spindles by means of theratchet drives to achieve a uniform tightening torque without amechanical torque limiter installed onto the ratchet drives. The torqueto be applied to the drive spindles is then solely dependent on thehydraulic fluid pressure provided, with which the ratchet drives aredriven. As the hydraulic fluid pressure is identical in all actuatorcylinders used to drive the ratchet drives, the maximum torque to beinduced to the individual drive spindles also is identical.

In one example embodiment, it is provided that, to realize therespective torque limiter assigned to each drive spindle, the outputwheel meshes with the splines of the actuating wheel by means of outersplines, while said output wheel on its inner side fits closely againsttwo coupling discs under a preload defining the torque limit. Accordingto one possible design, the coupling discs are inclined to each otherwith their coupling surfaces, whereby an output wheel accommodation isprovided. The incline can be linear or curved, as provided in oneexample embodiment. The inner contour of the output wheel iscomplementary to the cross-sectional contour of the coupling surfaces.The preload typically is provided by at least one compression springacting on a coupling disc, while the other coupling disc is supported ona thrust bearing. If desired, it may be provided that the preload actingon the coupling discs is adjustable. As a rule, this will not benecessary, since the torque transferred by means of the actuator unitfor driving the drive spindles is not the important factor fortightening the screw connections. Rather, it is essential that thetorque limit is identical for all drive spindles when driving the drivespindles by means of the actuator unit.

Preferably, the actuator unit is a module of the torque wrench formultiple bolts or nuts, and can be detachably connected to a drive blockcontaining the ratchet drives. In such an embodiment of the torquewrench for multiple bolts or nuts, the components of the actuator unitcan be located in a housing comprising an upper and a lower part.

In a preferred example embodiment of the modular design of the actuatorunit of the torque wrench for multiple bolts or nuts, the drive spindlesare supported and held in a drive block, which contains the ratchetdrives, and protrude from the same on both sides with respective drivesections. The torque-applying tools are mounted on the drive sections ofthe drive spindles protruding from one side. The actuator unit, then, isconnected to the other side of the drive block in such a design and actson the other drive sections. The torque-applying tools typically aredetachably connected to the drive spindle, as is the actuator unit. Inthis respect, this torque wrench for multiple bolts or nuts can beswitched from a tightening operation to a loosening operation, byremoving the torque-applying tools from one set of drive sections of thedrive spindles, and removing the actuator unit from the other drivesections of the drive spindles, and then connecting said components tothe drive sections on the respective other side.

In a further development of such a torque wrench for multiple bolts ornuts, it is provided that, in addition to the ratchet drive, a lockingratchet for locking the drive spindle acts on each drive spindle to keepit from turning back when performing a return stroke movement of thedrive ratchet, which locking ratchets are arranged in a locking bracketpenetrated by the drive spindles, and that the locking bracket has meansfor loosening the locking ratchets.

In this torque wrench for multiple bolts or nuts, a locking ratchet actson each drive spindle, in addition to the ratchet drive. The ratchet ofthe ratchet drive, as well as the locking ratchet, respectively act onthe drive spindle in the same direction. Both the pawl of the ratchetdrive and the locking pawl of the locking ratchet are in engagement withouter splines of the drive spindle. The pawl of the ratchet drive andthe locking pawl of the locking ratchet engage with the teeth of thedrive spindle in equal measure. This means that, when performing areturn stroke of the ratchet lever of the ratchet drive, the lockingratchet prevents the drive spindle from springing back, for example dueto a previously induced torsional force of the drive spindle. Thelocking ratchets of this torque wrench for multiple bolts or nuts arearranged in a locking bracket, which is penetrated by the drivespindles. The locking bracket thus follows the arrangement of the drivespindles arranged around a center. Typically, the locking bracket isannular. However, an embodiment in which it only extends across acircular segment also is possible. Even in such an embodiment, the drivespindles are arranged around a center, however, not in a ring structurebut only in a circular segment structure. Providing a locking bracket inwhich the locking ratchets are arranged makes it possible that saidlocking bracket has means for loosening the locking ratchets. With thesemeans, the locking pawls can be moved out of their position engagingwith outer splines of the drive spindle. For this purpose, the lockingpawls are typically held in the locking bracket translationally againstthe force of a return spring, against which spring force the lockingpawls are moved out of their locking position, in which their hooksengage with outer splines of the drive spindle. The guiding of a lockingpawl within the locking bracket typically is provided by the walls ofthe locking chamber inside which such a locking pawl is mounted. Such alocking chamber represents an expansion in the radial direction to adrive spindle opening.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the present disclosure is described on the basis of anexample embodiment with reference to the attached drawings, wherein:

FIG. 1 shows a longitudinal-section view through a torque wrench formultiple bolts or nuts;

FIG. 2 shows a cross-section along line A-B of the torque wrench formultiple bolts or nuts of FIG. 1;

FIG. 3 shows another cross-section along the line C-D through the torquewrench for multiple bolts or nuts of FIG. 1 to represent a lockingdevice for locking the drive spindles in a locking position; and

FIG. 4 shows the representation of FIG. 3 with unlocked locking devices.

DETAILED DESCRIPTION

In the example embodiment shown in the drawings, a torque wrench formultiple bolts or nuts 1 is of a modular design and comprises a driveblock 2 as the first module, a locking unit 3 as the second module, andan actuator unit 4 as the third module. The individual modules 2, 3, 4are explained below. Even if, within the context of these explanations,these are combined for forming the torque wrench for multiple bolts ornuts 1, the individual modules 2, 3, 4 can also be used independently ofeach other together with differently designed components of a torquewrench for multiple bolts or nuts. For example, the functionalityachieved with the locking unit 3 can also be combined in connection withanother drive block or also without actuator unit or with a differentlyformed actuator unit. The same applies to the actuator unit 3.

The Drive Block

In the example embodiment shown here, eight drive spindles 5 areprovided in the drive block 2. These are arranged annularly around acenter. These are rotatably supported and held in the drive block 2. Thedrive block 2 has a cylindrical outer lateral surface. In the sectionalrepresentation of FIG. 1, two drive spindles 5 are shown in a sectionalview, while three others, positioned behind them, are recognizable in afront view or partial view. The drive spindle 5 shown on the left inFIG. 1 and its drive are described in more detail in the following.These explanations also apply equally to the other drive spindles 5,which are designed in the same way as the drive spindle and its drivedescribed below.

In the example embodiment shown here, the drive block 2 is provided bytwo block discs 6, 6.1. The drive spindle 5 penetrates the block discs6, 6.1, which are connected to each other, and protrudes from them onboth ends. These sections of the drive spindle 5 protruding from thedrive block 2 are referenced as drive sections 7, 7.1 in the context ofthese explanations. As torque-applying tool, a socket 8 having an innercontour is seated on the drive section 7 in a torque-transferringmanner, which drive section 7 in FIG. 1 protrudes from the bottom of thedrive block 2. The socket 8 is detachably held on the drive section 7 ina manner known per se, specifically held by a locking ring 10pre-tensioned by a compression spring 9. If the locking ring 10 is movedin the direction of the drive block 2, the locking effect caused by aball not shown in the drawing is released, such that the socket 8 can bedetached from the drive section 7. The drive spindle 5 is supported inthe drive block 2 by bearings, which can also have seals at theiroutward-facing sides, which prevent an entry of contamination into thebearings of the drive spindle 5.

A ratchet drive serves for driving the drive spindle 5, as is describedmore clearly by means of the cross-sectional representation of FIG. 2.In the example embodiment shown here, four ratchet drives are housed inthe upper block disc 6.1 and four further ratchet drives in the lowerblock disc 6. The respective ratchet drives for the individual drivespindles 5 are of the same design.

To provide a drive by means of such a ratchet drive, the drive spindle 5has circumferential, asymmetrical outer splines 11 in its drive section,as is typical for ratchet drives. The longer spline flanks point in thedrive direction of the drive spindle 5. The shorter spline flanks pointin the opposite rotational direction. The ratchet drive comprises apiston-cylinder arrangement 12, the piston rod 13 of which acts on aratchet lever 14. A piston 13.1 supporting the piston rod 13 is locatedin a cylinder housing provided by a screw-in cylinder 15. The cylinderhousing 15 has two fluid connectors, of which a fluid connector 16 isvisible in the sectional view of FIG. 2. This fluid connector 16 opensinto the bottom area of a hole drilled in the drive block 2, whichreceives the screw-in cylinder 15. Hydraulic fluid is fed into thecylinder housing 15 via the fluid connector 16 for moving the piston13.1 with its piston rod 13 to perform a forward stroke. The hydraulicconnector for the return stroke opens radially into the screw-incylinder 15 at the side of the piston 13.1 opposite to the fluidconnector 16. The piston rod 13 is connected to the ratchet lever 14 ina manner transferring both compressive and tensile forces, such that aforward stroke performed by the piston leads to a forward strokemovement by the ratchet lever 14. By performing a return stroke, theratchet lever 14 is returned to its position shown in FIG. 2. The piston13.1 is connected to the ratchet lever 14 via a push rod as an extensionof the piston rod 13. This push rod penetrates a hole in the ratchetlever 14, which extends in the direction of movement of the piston rod13. Between the push rod and the piston rod 13 is an actuating tappetwith which the piston rod 13 interacts for transferring a forward strokemovement against a bolt of the ratchet lever 14 providing theaforementioned hole that is penetrated by the push rod. The push rodpenetrates the hole. A retaining disc, for example a snap ring, islocated on the section of the push rod protruding from the hole, bymeans of which disc the ratchet lever 14 is moved along when the pistonrod 13 performs a return stroke movement.

A pawl 17 is inserted in the ratchet lever 14. The teeth of the pawl 17,which is under spring preload (not shown in the drawing), engage withthe outer splines 11 of the drive spindle 5. The teeth of the pawl 17are designed to be complementary to the outer splines 11 of the drivespindle 5. During a forward stroke of the piston rod 13, which leads toa rotation to the right of the ratchet lever 14, the drive spindle 5 ismoved clockwise. In the example embodiment shown here, the drive spindleis moved by one tooth when a forward stroke is performed. During areturn stroke, the ratchet lever 14, along with the pawl 17, is returnedin its position shown in FIG. 2, while the drive spindle 5 remains inits position into which it had been moved by the previously performeddrive movement.

The drive block 2 shown in FIG. 1 shows the stacked arrangement of theratchet drives offset at an angle in the two block discs 6, 6.1. Thedrive block 2 of the torque wrench for multiple bolts or nuts 1 has afirst hydraulic fluid connector for feeding hydraulic fluid from ahydraulic pump for performing the forward stroke and a second hydraulicconnector for feeding hydraulic fluid for performing the return stroke.These hydraulic connectors are not visible in the drawing. The hydraulicfluid connector for the forward stroke is connected to a fluiddistribution cavity designed as an annular duct 18 by means of a ductextending in the radial direction. The annular duct 18 is located in thewall of a central hole located in the drive block 2. The hole is filledwith a cylindrical fluid distributor 19. This distributor is crossed bytransverse bores 20 at the height of the annular duct 18. On both sidesof the annular duct 18, sealing rings are provided in slots for sealingthe lateral surface of the fluid distributor 19. The annular duct 18serves for supplying hydraulic fluid required for the forward stroke ofthe piston-cylinder arrangements 12 of the ratchet drives arranged inthe block disc 6.1. Fluid ducts also open into the annular duct 18,which fluid ducts establish a connection between the annular duct 18 andthe piston-cylinder arrangements 12 installed in the block disc 6.1 forthe forward stroke. A small section 21 of such a line is visible in FIG.2, as it is inclined relative to a horizontal plane. The transverse bore22, which is adjacent to the section 21, is used to establish a fluidconnection between the radial extension of the section 21 and the fluidconnector 16 or the cylinder housing 15. This transverse bore 22 isclosed at its end that is opposite to the screw-in cylinder 15. Theaforementioned transverse bores 20 serve to also supply thepiston-cylinder arrangement of the block disc 6 with hydraulic fluid forthe forward stroke. Said bores open into a central fluid duct 23,through which a fluid path is established to the same plane as a secondannular chamber 24 in the lower block disc 6. Four fluid ducts also openinto the annular chamber 24 for establishing a fluid connection betweena first fluid connector of the cylinder housings received in the blockdisc 6.

The piston-cylinder arrangements 12 of the drive block 2 are alldesigned identically. Therefore, the same amount of hydraulic fluid isrequired for performing a forward stroke of each piston-cylinderarrangement.

The hydraulic fluid connection for feeding hydraulic fluid for thereturn stroke opens into an annular fluid distributor 25 connected tothe top of the block disc 6.1. The fluid distributor 25 provides anotherannular duct 26, into which fluid ducts (not shown in detail in thedrawing) open, which fluid ducts are connected to respective backstrokefluid connectors of a screw-in cylinder 15 at their other end. While thefluid ducts for feeding hydraulic fluid to the piston-cylinderarrangements 12 largely extend in the radial direction, the fluid ductsfor feeding the hydraulic fluid for performing a return stroke largelyextend in the vertical direction and thus in the direction of thelongitudinal extension of the drive spindles 5.

In the example embodiment shown here, the annular duct 26 is provided bytwo annular bodies 27, 28 arranged concentrically to each other. Thegeometry of the annular duct 26 is located in the inner wall of theannular body 27 located on the outer side as seen in the radialdirection. The inner side of the annular duct 26, as seen in the radialdirection, is closed by the outer lateral surface of the second annularbody 28. Ring seals arranged adjacent to the annular channel 26 ensurethe necessary tightness. The annular body 28 is penetrated by the drivespindles 5, as is visible in FIGS. 1 and 3.

The Locking Unit

In the example embodiment shown here, the inner annular body 28 at thesame time represents a locking bracket. The drive spindles 5 penetratethe annular locking bracket 28. The locking bracket 28 bears respectivelocking ratchets 29 associated with each drive spindle 5 for locking therespective drive spindle 5 against turning back or springing back whenthe drive ratchet performs a return stroke movement, i.e., when the pawlwith its teeth is moved away from the outer splines 11 of the drivespindle 5. Each locking ratchet 29 comprises a locking chamber 30 as anextension of the opening 31, which is penetrated by the drive spindle 5.A locking pawl 32 is located in the locking chamber 30, the teeth ofwhich locking pawl 32 under spring-load (not shown in the drawings)engage with the outer splines 33, which also are present at this sectionof the drive spindle 5. The outer splines 33 and the outer splines 11 ofthe drive spindle 5 are asymmetrical with the same orientation and aredesigned with the same number of teeth. The same applies to theoperational direction of the locking pawl 30 and the pawl 17. Thelocking ratchet 29 has the effect that the locking ratchet 29 remains inits locking position when a return stroke of the drive ratchet isperformed. This makes possible an application of torque to the drivespindle 5 and thus to the torque-applying tool, designed as a socket 8in the example embodiment shown here, and to a bolt to be tightened insuch a measure that torsional force is exerted onto the bolt and/or thedrive spindle 5. Due to the blocking effect of the locking ratchet 29,an otherwise unavoidable springing back of the torsion introduced intothe drive spindle 5 and/or the bolt is effectively prevented when areturn stroke is performed.

The locking pawl 32 is designed T-shaped in its cross section, whereinthe middle portion bears the locking teeth interacting with the outersplines 33 of the drive spindle 5. The sections adjacent to both sideseach have an actuating area with which an actuating lever 34 makescontact. The actuating lever 34 serves the purpose of moving the lockingpawl 29 out of the position in which its teeth engage with the outersplines 33 of the drive spindle 5, when it is to be unlocked. Theactuating lever 34 is held with its radially outward end in a returnlever accommodation 35 of the locking bracket 28. Although the lockinglever 34 is designed as an angle, as shown in FIG. 3, it penetrates thelocking bracket 28 in an essentially radial direction and with anactuating section 36 protrudes from the locking bracket 28 toward theinside, as seen in the radial direction. The actuating lever 34 isrouted in an actuating lever channel 37 of the locking bracket 28. Thelocking channel 37 has sufficient clearance in the circumferentialdirection of the locking bracket 28 to allow a movement of the actuatinglever 34 to move the locking pawl 29 away from the drive spindle 5,specifically move it far enough away that the engagement of teeth of thelocking pawl 29 with the outer splines 33 of the drive spindle 5, whichotherwise is effected by the spring load, can be released. Furtherinward, as seen in the radial direction, from the locking bracket 28 isan actuating ring 38, which in turn has a return lever accommodation 39for the actuating section 36 of the actuating lever 34. The actuatingring 38 can be rotationally displaced relative to the locking bracket28, as indicated by an arrow in FIG. 3. An actuating rod 40 serves fordisplacing the actuating ring 28, which rod bears an actuating cam 41 atits end portion engaging with the actuating ring 38. The actuating rod40 is routed outward through the locking bracket 28, the outer annularbody 27 and through a housing 42, and bears a handle 43 at its endprotruding from the outer housing 42, via which handle 43 the actuatingrod 40 can be rotated for displacing the actuating ring 38. FIG. 3 showsthe locking bracket 28 with its locking ratchets 29 and the actuatingring 38 in the tightening position of the torque wrench for multiplebolts or nuts 1, in which position the locking ratchets 29 engage withthe outer splines 33 of the drive spindle 5 in a manner that locks thelatter.

To push back the locking pawls 30 from their position in which theyengage with the outer splines 31 of the drive spindles 5, the actuatingrod 40 is rotated by means of the handle by about 180 degrees. Due tothe engagement of the eccentrically designed actuating cam 41 with anactuating cam recess 44 of the actuating ring 38, the actuating ring 38is adjusted counterclockwise, whereby the actuating levers 34 fittedagainst the actuating areas move the locking pawls 32 away from therespective drive spindle 5. If a torsional force acts on the lockingpawls 32 via the drive spindles 5 and it is not easily possible torelease the locking mechanism by turning the actuating rod 40, aspreviously described, the piston cylinder arrangements 12 are controlledto perform a forward stroke, such that the torsional force acting on thelocking pawls 32 is reduced. The torque wrench for multiple bolts ornuts 1 can then easily be removed from the tightened bolts.

The locking unit 3 thus makes it possible to tighten screw connectionswith a particularly high torque using the torque wrench for multiplebolts or nuts 1, in particular with such a torque at which the screwconnection remains tight even when exposed to a certain torsion of thecomponents that were fastened together.

The Actuator Unit

The actuator unit 4 acts on the drive sections 7.1 of the drive spindles5 opposite to the torque-applying tools (see FIG. 1). The actuator unit4 serves for inducing a rotational movement in the drive spindles 5, inorder to bring the inner contour of the sockets 8 seated on the drivesections 7 into alignment with the outer contour of the individualbolts. In addition, the actuator unit 4 serves the purpose of bringingthe bolts to be tightened by means of the torque wrench for multiplebolts or nuts 1 to a uniform preload before the hydraulic tighteningprocess.

The actuator unit 4 comprises a central actuating wheel 45 with a drivecontour 46 located centrically within said wheel, into which contour,for example, the square shaft of a ratchet or another manual orelectrical tool can be inserted. By turning the actuating wheel 45, thedrive spindles 5 can be driven via respective torque limiters. Theactuating wheel 45 bears outer splines 47, which mesh with an outputwheel 48 that is seated on the drive section 7.1. The output wheel 48has corresponding, complementary teeth 49 and acts on two coupling rings50, 50.1 with its radial inner side having two coupling surfaces. Theinside of the output wheel 48 is conically tapered for this purpose andacts against complementary inclined coupling surfaces of the couplingrings 50, 51. The upper coupling ring 50 in FIG. 1 acts in the directionof the longitudinal axis of the drive spindle 5 against a counterbearing plate 51. The lower coupling ring 50.1 is under the preload of acompression spring 52 acting on it, which spring is supported on acounter bearing with its other end; through this compression spring 52,the coupling ring 50.1, via the output wheel 48, acts in the directionof the other coupling ring 50. Thus, the force transfer from the outputwheel 48 to the coupling rings 50, 50.1 seated on the drive section 7.1of the drive spindle 5 in a torque-transferring manner is limited by thecompression spring 52.

As the actuating wheel 45 drives all drive spindles 5 in the samemanner, a low torque suffices to bring the torque-applying tools seatedon the opposite drive section 7 of the drive spindles 5 into theposition required for engagement with, for example, the head of a bolt.In addition, the bolts are tightened at the same preload by the drivevia the actuating wheel 45. If a screw bolt is tightened with a certainpreload, the slip coupling installed on the respective drive spindle 7.1operates as a torque limiter, such that this drive spindle 5 is notturned further by additional rotary movements of the actuating wheel 45,wherein, on the other hand, the other drive spindles, which can stilltransfer the torque transferred via the torque limiter, are turnedfurther, specifically until their respective torque limiters formed bythe coupling discs 50, 50.1 also are triggered. Thus, a uniform torquelimitation of the torque transferred via the actuating wheel 45 to thedrive spindles 5 is achieved in a simple manner.

Other Operational Devices

The torque wrench for multiple bolts or nuts 1 is associated with ahydraulic unit and a control device for controlling the hydraulic unitfor its operation. The hydraulic unit includes a hydraulic pump, a fluidtank for the storage of hydraulic fluid, typically hydraulic oil, aswell as a fluid pressure output for the forward stroke and another fluidpressure output for the return stroke. In addition, the hydraulic unithas a flow measurement device for detecting the hydraulic fluid quantityconveyed, which is used to detect said quantity during the operation ofthe hydraulic unit. According to a preferred operating method of thetorque wrench for multiple bolts or nuts, the hydraulic unit iscontrolled dependent on fluid flow rates, based on information from itsflow measurement device. This ensures that a switch from a forwardstroke to a return stroke of the hydraulic actuator cylinders of thetorque wrench for multiple bolts or nuts takes place only when thepredefined hydraulic fluid quantity has been conveyed. This predefinedhydraulic fluid flow quantity corresponds to the hydraulic fluid volumerequired to move the piston arranged in each hydraulic actuatingcylinder from its one end position to its other end position. Thisensures that a switch from a forward stroke movement to a return strokemovement takes place only when all pistons of the ratchet drives haveactually been moved in equal measures. The same applies to a switch froma return stroke movement to a forward stroke movement. When thehydraulic unit is controlled in this manner, it is therefore irrelevantwhether the desired stroke is carried out synchronously in all actuatorcylinders or with a small time offset. In order to be able to determinethe respective quantity of hydraulic fluid, the torque wrench formultiple bolts or nuts is actuated several times to perform of a strokebefore it is used to actually tighten or loosen a bolt. The respectivefluid volume conveyed is recorded therein. By repeating this processmultiple times, a reliable reference value for the fluid volume conveyedis obtained. This fluid quantity conveyed then determines the switchingtime. If in such an operation of the hydraulic unit of the torque wrenchfor multiple bolts or nuts the hydraulic fluid flow quantity requiredfor switching from a forward stroke movement to a return stroke movementcould no longer be conveyed, because at least one of the screwconnections to be tightened is already sufficiently tightened, causingthe actuator cylinder not to be moved further by means of the appliedhydraulic pressure, the hydraulic unit typically switches off. A furtherapplication of torque can then be carried out by manually controllingthe fluid conveyance until all screw connections are tightened with thedesired torque. If no more hydraulic fluid is conveyed, all screwconnections are tightened with the same torque, as the hydraulic oilpressure remains constant. In this mode of operation, the force withwhich the screw connections are tightened is dependent on the pressurewith which the hydraulic fluid is conveyed. With such a torque wrenchfor multiple bolts or nuts, screw connections can also be tightened withvery high torques.

The operation of the hydraulic unit and thus of the torque wrench formultiple bolts or nuts can also be carried out at different pressurelevels. It is possible to perform a first tightening step with only alow hydraulic pressure (a few bar). This step of tightening the boltsmerely serves for the torque-applying tools to mate their contour to thecomplementary fastening elements to be driven, for example the head of abolt, and that all screw connections are brought into a same initialstate with respect to their fastening position. Once this is achieved,the actual tightening of the screw connections takes place. For thispurpose, the hydraulic pressure of the hydraulic unit is raised to thepressure corresponding to the torque to be applied. Herein, it isentirely possible to apply pressures from 600 to 800 bar. Of course, itis also possible to provide higher pressures. The tightening process iscarried out by means of the fluid control process dependent on fluidquantities conveyed, as already described above.

LIST OF REFERENCE NUMBERS

1 Torque wrench 2 Drive block 3 Locking unit 4 Actuator unit 5 Drivespindle 6, 6.1 Block disc 7, 7.1 Drive section 8 Socket 9 Compressionspring 10 Locking ring 11 Outer splines 12 Piston-cylinder arrangement13 Piston rod 13.1 Piston 14 Ratchet lever 15 Cylinder housing 16 Fluidconnector 17 Pawl 18 Annular duct 19 Fluid distributor 20 Transversebore 21 Section 22 Transverse bore 23 Fluid duct 24 Annular chamber 25Fluid distributor 26 Annular duct 27 Ring body 28 Annular body/lockingbracket 29 Locking ratchet 30 Locking chamber 31 Opening 32 Locking pawl33 Outer splines 34 Actuating lever 35 Return lever accommodation 36Actuating section 37 Actuating lever channel 38 Actuating ring 39 Returnlever accommodation 40 Actuating rod 41 Actuating cam 42 Housing 43Handle 44 Actuating cam recess 45 Actuating wheel 46 Drive contour 47Outer splines 48 Output wheel 49 Teeth 50, 50.1 Coupling ring 51 Counterbearing disc 52 Compression spring

1-26. (canceled)
 27. A multiplex bolting tool for multiple bolts or nutswith multiple drive spindles that are arranged around a center and areequipped or able to be equipped at an end with respectivetorque-applying tools, and a ratchet drive, associated with each drivespindle and driven by means of a hydraulic piston drive, for driving thedrive spindles, comprising: an actuator unit for inducing a rotarymovement in the drive spindles, the actuator unit having an actuatingwheel mounted rotatably about the axis of the center of the annulararrangement of the drive spindles as drive wheel, which drivesrespective output wheels fitted on the drive spindles, wherein drivingmovement of the actuating wheel is transmitted to the drive spindles viarespective torque limiters.
 28. The multiplex bolting tool of claim 27,wherein the output wheels are connected to the drive spindles via a slipcoupling for transferring drive force to the drive spindles in atorque-limited manner, and respective gear rings of the output wheelsmesh with outer splines of the actuating wheel.
 29. The multiplexbolting tool of claim 28, wherein the slip coupling of each drivespindle comprises two coupling discs seated on said drive spindle in atorque-transferring manner, each having a coupling surface inclinedrelative to the longitudinal extension of the drive spindle, whichcoupling surfaces are inclined to each other for forming an output wheelaccommodation, and also comprises the output wheel, which engages withthe output wheel accommodation with its inner side designedcomplementary to the coupling surfaces and which fits against thecoupling surfaces of the coupling discs under preload.
 30. The multiplexbolting tool of claim 29, wherein the coupling surfaces are curved inthe direction of their inclination.
 31. The multiplex bolting tool ofclaim 29, wherein the preload of the slip coupling is provided by acompression spring acting on one of the coupling discs.
 32. Themultiplex bolting tool of claim 29, wherein the preload of the slipcoupling is adjustable.
 33. The multiplex bolting tool of claim 27,wherein the actuating wheel has a drive contour for connecting a drivetool.
 34. The multiplex bolting tool of claim 27, further comprising adrive block, wherein the actuator unit is designed such that it can bedetachably connected to the drive block and components of the actuatorunit are received in a housing with an upper part and a lower part. 35.The multiplex bolting tool of claim 34, wherein the drive spindles aresupported and held in the drive block, each drive spindle having a drivesection protruding from the drive block at each end, wherein the drivesections of the drive spindles on one side of the drive block serve tobear the torque-applying tools, and the actuator unit is connected tothe other drive sections of the drive spindles.
 36. The multiplexbolting tool of claim 35, wherein, inside the drive block, pistons ofthe piston drives are routed in cylinder housings such that said pistonsare translationally displaceable in both directions, wherein piston rodsof the pistons are each kinematically connected to a ratchet lever fortransferring a forward stroke movement and a return stroke movement tothe respective ratchet levers with pawls, and wherein the drive blockhas at least one first fluid distribution cavity in a center areathereof, into which multiple fluid ducts located in the drive blockopen, said multiple fluid ducts each establish a fluid connectionbetween the at least one first fluid distribution cavity and a firstfluid input of one of the cylinder housings, and wherein, on a flat sideof the drive block, a fluid distributor with an annular duct connectedto a fluid supply duct is arranged as a second fluid distributioncavity, into which multiple fluid ducts open, said multiple fluid ductseach establish a fluid connection between the second fluid distributioncavity and a second fluid input of one of the cylinder housings.
 37. Themultiplex bolting tool of claim 36, wherein the at least one first fluiddistribution cavity located in the center area of the drive block isdesigned as an annular duct.
 38. The multiplex bolting tool of claim 36,wherein the drive block is composed of at least two block discs, whereinmultiple ratchet drives are arranged in each block disc.
 39. Themultiplex bolting tool of claim 36, wherein the at least one first fluiddistribution cavity comprises two first fluid distribution cavities,with a first fluid distribution cavity associated with each of the blockdiscs, and fluid connections are established between the two first fluiddistribution cavities by another fluid distributor.
 40. The multiplexbolting tool of claim 36, wherein the drive spindles bear spring-loadedsockets as the torque-applying tools.
 41. The multiplex bolting tool ofclaim 36, wherein the direction of movement of each piston rod of theratchet drives is the same as the direction of movement of therespective ratchet lever driven thereby, and the ratchet lever isdirectly driven by the piston rod.
 42. The multiplex bolting tool ofclaim 36, wherein the direction of movement of each piston rod of theratchet drives extends at an angle to the direction of movement of therespective ratchet lever driven thereby, and in order to transfer theforward stroke movement and the return stroke movement of the piston rodto the respective ratchet lever, a link is arranged between the pistonrod and the ratchet lever such that one end of the link is articulatedto the piston rod and the other end of the link is articulated to theratchet lever.
 43. The multiplex bolting tool of claim 36, wherein thelink is a lever of a two-bar toggle joint.
 44. The multiplex boltingtool of claim 36, wherein the multiplex bolting tool is associated witha hydraulic unit comprising a hydraulic pump, a fluid tank, a fluidpressure output for the forward stroke and a further fluid pressureoutput for the return stroke, and at least one flow measurement deviceas well as a control unit for controlling the hydraulic unit, by whichcontrol device the hydraulic unit, during operation of the multiplexbolting tool, is switched between a forward stroke conveyance and areturn stroke conveyance dependent on a fluid quantity conveyed.
 45. Themultiplex bolting tool of claim 27, further comprising locking ratchetsfor locking the drive spindles, each locking ratchet acts on one of thedrive spindles, in addition to the ratchet drive, to keep the drivespindle from turning back when the ratchet drive performs a returnstroke movement, wherein the locking ratchets are arranged in a lockingbracket penetrated by the drive spindles, and the locking bracket hasmeans for loosening the locking ratchets.
 46. The multiplex bolting toolof claim 45, wherein each drive spindle opening of the locking bracketcomprises a locking chamber in which a locking pawl acting on the drivespindle under spring load is received.
 47. The multiplex bolting tool ofclaim 46, wherein the locking pawl has at least one actuating areafacing the drive spindle, against which actuating area a return lever isfitted for moving the locking pawl away from a position in which thelocking pawl locks the drive spindle.
 48. The multiplex bolting tool ofclaim 47, wherein the locking pawl has two actuating areas which enclosea middle part supporting teeth of the locking pawl.
 49. The multiplexbolting tool of claim 47, wherein each return lever associated with thelocking ratchets protrudes with one end into a return leveraccommodation of the locking bracket and with its other end protrudesfrom the locking bracket in the radial direction and engages with areturn lever accommodation of an actuating ring which is concentricallyrotatable to the locking bracket for displacing the return levers. 50.The multiplex bolting tool of claim 49, wherein the actuating ring isarranged on an inner side of the locking bracket, as seen in the radialdirection, and has an actuating cam recess in which an actuating cam isheld rotatably relative to the locking bracket for adjusting theactuating ring.
 51. The multiplex bolting tool of claim 50, wherein theactuating cam is provided on an actuating rod, which extends in theradial direction and penetrates the locking bracket, with an end of theactuating rod protruding from the locking bracket in the radialdirection having a handle.
 52. The multiplex bolting tool of claim 49,wherein the return lever has an edge pointing to an actuating area ofthe locking pawl, starting from which a first bar of the return leverextends to the return lever accommodation of the locking bracket and asecond bar of the return lever extends into the return leveraccommodation of the actuating ring.